Spinal fixation element rotation instrument

ABSTRACT

A spinal fixation element rotation instrument with two lever arms is provided. The lever arms are connected to each other at distal ends thereof. The second lever arm rotates relative to the first lever arm. The distal ends of the first and second lever arms are adapted to couple to a spinal fixation element. The distal ends of the lever arms may have a dual ratchet feature that prevents rotation in a set direction. When one arm rotates back and forth, the other arm is held stationary. As a result, the spinal fixation element rotates in a predetermined direction and is prevented from rotating back toward its initial position. The direction of the rotation of the spinal fixation element may be set using knobs or switches provided at a proximal end of one or both of the lever arms.

FIELD OF THE INVENTION

The present invention relates to spinal connection devices used inorthopedic surgery. More particularly, the present invention may relateto a spinal fixation element rotation instrument with dual lever armsthat couple to and rotate a spinal fixation element when positioning thespinal fixation element through bone anchors placed on vertebrae.

BACKGROUND OF THE INVENTION

Spinal fixation systems may be used in surgery to align, adjust and/orfix portions of the spinal column, i.e., vertebrae, in a desired spatialrelationship relative to each other. Many spinal fixation systems employa spinal fixation element, e.g. a spinal fixation rod, for supportingthe spine and for properly positioning components of the spine forvarious treatment purposes. Vertebral bone anchors, comprising pins,bolts, screws, and hooks, engage the vertebrae and connect thesupporting spinal fixation element to different vertebrae. The size,length and shape of the spinal fixation element depend on the size,number and position of the vertebrae to be held in a desired spatialrelationship relative to each other by the apparatus.

Spinal fixation elements can be anchored to specific portions of thevertebra. Since each vertebra varies in shape and size, a variety ofanchoring devices have been developed to facilitate engagement of aparticular portion of the bone. Pedicle screw assemblies, for example,have a shape and size that is configured to engage pedicle bone. Suchscrews typically include a threaded shank that is adapted to be threadedinto a vertebra, and a head portion having a spinal fixationelement-receiving portion for receiving a spinal fixation element. Aset-screw, plug, cap or similar type of closure mechanism is used tolock the spinal fixation element into the spinal fixationelement-receiving portion of the pedicle screw.

In conventional spinal surgery, first, anchoring devices are attached tovertebra, then a spinal rod is aligned with the anchoring devices andsecured. For example, for conventional pedicle screw assemblies, firstthe engagement portion of each pedicle screw is threaded into avertebra. Once the pedicle screw assembly is properly positioned, aspinal fixation rod is seated in the rod-receiving portion of eachpedicle screw head. The rod is locked into place by tightening a cap orsimilar type of closure mechanism to securely interconnect each pediclescrew to the fixation rod. This type of conventional spinal surgicaltechnique usually involves making a surgical access opening in the backof the patient. Because exact placement of the screw assemblies dependson a patient's particular bone structure and bone quality, the exactposition of all screw assemblies cannot be known until after all theassemblies are positioned. Adjustments, such as bending, are made to thespinal rod to ensure that it aligns with each screw assembly.

When placing the spinal fixation element in a long construct, the spinalfixation element may be inserted in an inverted orientation tofacilitate insertion and positioning of the spinal fixation elementbelow fascia. Consequently, the spinal fixation element needs to berotated prior to final positioning in order to match the curvature ofthe spine. The contemporary medical devices, such as spinal fixationelement holders, do not accommodate the rotation of the spinal fixationelement while performing a minimally invasive procedure. Rotating thespinal fixation element percutaneously typically requires an additionalskin incision or increasing the size of the existing skin incision.Additionally, it is desirable to make minimal rotary adjustments forbetter control. Currently, surgeons have to select a long rod to providea holding surface when the rod is placed through the skin incision. Theextra portion of the rod is cut in situ, extending the surgery time andposing the risk of cutting the rod at an unintentional location.

The contemporary medical devices also require re-engagement of thedevice to the spinal fixation element multiple times and often a secondinstrument is required during the re-engagement to prevent the spinalfixation element from slipping back toward the initial position.Therefore, there is a need for an instrument that will accommodate therotation of a spinal fixation element while preventing the spinalfixation element from rotating back toward the initial positionfollowing adjustment during a minimally invasive procedure.

SUMMARY

Embodiments of the present invention provide a spinal fixation elementrotation instrument that allows controlled rotation of spinal fixationelements. The spinal fixation element rotation instrument may includetwo lever arms connected to each other at a distal end thereof. Thefirst arm, i.e. the holder, is held stationary while the second arm,i.e. the driver, is configured to rotate in a predetermined directionrelative to the first arm. The driver rotates the spinal fixationelement within the bone anchors or the extensions thereof while theholder prevents the spinal fixation element from rotating back towardits initial position. The spinal fixation element rotation instrumentrotates the spinal fixation element to steer the spinal fixation elementthrough one or more bone anchors attached to vertebrae. The spinalfixation element rotation instrument may also force the bone anchors tomove the vertebrae attached thereto to bring the spine into alignment.

According to a first aspect of the invention, an instrument for rotatinga spinal fixation element is provided. The instrument includes a firstlever arm and a second lever arm. A distal end of the first lever arm isadapted to couple to the spinal fixation element. The second lever armis rotatably coupled to the first lever arm at the distal end thereof. Adistal end of the second lever arm is adapted to couple to the spinalfixation element. The second lever arm rotates relative to the firstlever arm, about a central axis of the distal ends of the first leverarm and the second lever arm to rotate the spinal fixation element froman initial position to a rotated position.

According to various aspects of the present invention, the first leverarm includes a first ratchet and the second lever arm includes a secondratchet forming a dual ratchet mechanism that prevents the spinalfixation element from rotating back toward the initial position. Theinstrument may further include an extension element. The extensionelement has a distal end adapted to couple to the spinal fixationelement and a proximal end adapted to couple to the instrument. Aportion of the extension element fits through a skin incision at atarget site to guide the spinal fixation element under skin.

According to another aspect, the second lever arm may further include afirst section, a second section and an attachment mechanism. Theattachment mechanism attaches the first section to the second section sothat the first section is rotatable relative to the second section abouta central axis of the attachment mechanism. The central axis of theattachment mechanism is perpendicular to the central axis of the distalends of the first lever arm and the second lever arm.

According to yet another aspect, the instrument may also include a firstswitch provided on a proximal end of the first lever arm. The firstswitch, when positioned at a first position, allows the first ratchet torotate clockwise. The first switch, when positioned at a secondposition, allows the first ratchet to rotate counterclockwise. Theinstrument may also include a second switch provided on a proximal endof the second lever arm. The second switch, when positioned at a firstposition, allows the second ratchet to rotate clockwise. The secondswitch, when positioned at a second position, allows the second ratchetto rotate counterclockwise. The first ratchet and the second ratchetlock each other when the first switch is at the first position and thesecond switch is at the second position. At the locked out position, thefirst ratchet and the second ratchet prevent the spinal fixation elementfrom rotating.

According to another aspect, a method for percutaneous positioning of aspinal fixation element through a plurality of bone anchors placed belowfascia is provided. The plurality of bone anchors have an openingadapted to couple to the spinal fixation element. A proximal end of thespinal fixation element is coupled to a spinal fixation element rotationinstrument including two lever arms connected to each other at a distalend of the spinal fixation element rotation instrument. The second leverarm rotates relative to a first lever arm about a central axis of thedistal end of the spinal fixation element rotation instrument. A distalend of the spinal fixation element is inserted through an incision inproximity of a first bone anchor. The spinal fixation element is guidedthrough the opening of the first bone anchor and a second bone anchoradjacent to the first bone anchor. The spinal fixation element isrotated within the distal end of the spinal fixation element rotationinstrument using the spinal fixation element rotation instrument toaccommodate the bone anchors.

According to another aspect of the present invention, a dual ratchetspinal fixation element rotation instrument holder is provided. The dualratchet spinal fixation element rotation instrument includes a firstratchet and a second ratchet connected to the first ratchet at a distalend thereof. The first ratchet and the second ratchet are configured tocouple to a spinal fixation element or to an extension element coupledto the spinal fixation element. One of the first ratchet or the secondratchet rotates the spinal fixation element in a first direction from aninitial position to a rotated position. Other of the first ratchet orthe second ratchet prevents the spinal fixation element from rotatingback toward the initial position.

According to yet another aspect of the present invention, a method forpositioning of a spinal fixation element through a plurality of boneanchors placed below fascia is provided. The plurality of bone anchorshave an opening adapted to couple to the spinal fixation element. Aproximal end of the spinal fixation element is coupled to a spinalfixation element rotation instrument having a lever arm. The spinalfixation element is placed through the opening of the first bone anchor.The spinal fixation element is guided though a second bone anchor. Thelever arm is rotated in a first direction to effect rotation of thespinal fixation element about a central axis of the spinal fixationelement in the first direction to a rotational position. The lever armis rotated in a second direction, opposite the first direction, whilemaintaining the spinal fixation element in the rotational position.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description and apparentfrom the accompanying drawings, in which like reference characters referto the same parts throughout the different views. The drawingsillustrate principles of the invention and, although not to scale, showrelative dimensions.

FIGS. 1A-1B illustrate an exemplary spinal fixation element rotationinstrument, an exemplary extension element and an exemplary spinalfixation element;

FIG. 2A illustrates a cross-sectional view of an exemplary extensionelement coupled to an exemplary spinal fixation element rotationinstrument;

FIG. 2B illustrates a cross-sectional view of a carrier of the exemplaryextension element illustrated in FIG. 2A;

FIG. 2C illustrates a cross-sectional view of the distal end of theexemplary spinal fixation element rotation instrument illustrated inFIG. 2A;

FIGS. 3A-3B illustrate exemplary spinal fixation elements according tovarious embodiments of the present invention;

FIGS. 4A-4C illustrate an exemplary coupling mechanism that couples thespinal fixation element to the extension element;

FIGS. 5A-5B illustrate another exemplary coupling mechanism that couplesthe spinal fixation element to the extension element;

FIGS. 6A-6B illustrate a first switch provided on the first lever armand a second switch provided on the second lever arm;

FIGS. 6C-6D illustrate a first ratchet and a second ratchet provided ata distal end of the spinal fixation element rotation instrumentaccording to an exemplary embodiment of the present invention;

FIG. 7 illustrates an exemplary spinal fixation element rotation elementcoupled to the exemplary extension element that is coupled to theexemplary spinal fixation element;

FIGS. 8A-8B illustrate an exemplary configuration of a second lever armincluding a first section and a second section;

FIGS. 9A-9B illustrate the second section of the second lever arm at anangled position relative to the first section of the second lever arm;

FIGS. 10A-10B illustrate the placement of the spinal fixation elementthrough a plurality of bone anchors using the spinal fixation elementrotation instrument; and

FIGS. 11A-11B are a flow diagram of placing a spinal fixation elementthrough a plurality of bone anchors.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention provide an improvedspinal fixation element rotation instrument to be used in placing aspinal fixation element through a plurality of vertebral bone anchorsduring a minimally invasive surgery for correcting a deformity or adegenerative spine disorder. One of ordinary skill in the art willrecognize that the present invention is not limited to use in spinalsurgery, and that the instrument and methods described herein can beadapted for use with any suitable surgical device to be placed in adesired position in a variety of medical procedures.

The spinal fixation element rotation instrument of some of the exemplaryembodiments has two lever arms that are connected to each other atdistal ends thereof. Each lever arm rotates relative to the other leverarm. The distal ends of the first and second lever arms are adapted tocouple to a spinal fixation element or an extension element that couplesto the spinal fixation element. The spinal fixation element is securedwithin the distal ends of the first and second lever arms. The distalends of the lever arms may have a dual ratchet feature that preventsrotation of the spinal fixation element in a set direction. When onearm, i.e. the driver, rotates back and forth, the other arm, i.e. theholder, is held stationary. As a result, the spinal fixation elementrotates in a predetermined direction from an initial position to arotated position and is prevented from rotating back toward the initialposition.

The rotational direction of the lever arms, thus the rotationaldirection of the spinal fixation element, may be set using knobs orswitches provided at a proximal end of one or both of the lever arms.Setting the switch of the driver arm to a first position may allow thedriver arm to rotate the spinal fixation element clockwise. Similarly,setting the switch of the driver arm to a second position may allow thedriver arm to rotate the spinal fixation element counterclockwise.

According to various embodiments of the present invention, the switchesprovided on the first and second lever arms may be set in a positionthat locks the rotation of the lever arms. In the locked out position,the lever arms no longer have the ratcheting feature and the spinalextension element is prevented from rotating within the distal ends ofthe lever arms. Therefore, if the user would like to change therotational direction of the spinal fixation element, the user would haveto change the rotational direction of one of the driver arm or theholder arm. If the user only changes the rotational direction of both ofthe driver arm and the holder arm, the instrument will be in the lockedout position.

The driver arm of the spinal fixation element rotation instrument may beprovided with two sections attached to each other via a hinge or aloaded spring mechanism. The hinge may allow the first section to rotateabout a central axis of the hinge, relative to the second section. Thisway, the first section may be moved away from the screw extensionsproviding clearance during spinal fixation element rotation and enablingthe user to relocate the first section to better suit the conditions ofthe procedure.

FIG. 1A illustrates a profile view of an exemplary spinal fixationelement rotation instrument 100, an exemplary extension element 150 andan exemplary spinal fixation element 160. A proximal end 154 of theextension element 150 couples to the spinal fixation element rotationinstrument 100 and a distal end 152 of the extension element 150 couplesto the spinal fixation element 160.

As illustrated in FIGS. 1A-1B, the extension element 150 includes asleeve 156 provided around a carrier 158. The carrier 158 is adapted tocouple to the spinal fixation element 160. The carrier 158 may include acoupling feature 140, such as a leaf spring, for tightly holding thespinal fixation element 160. The coupling feature 140 preventsinadvertent decoupling of the spinal fixation element 160 from theextension element 150. For example, the spinal fixation element 160 maybe coupled to the extension element 150 via a spring loaded tooth.Alternatively, the coupling feature 140 may grab on the surface featuresprovided at the proximal end 164 of the spinal fixation element 160.Exemplary coupling mechanisms coupling the extension element 150 and thespinal fixation element 160 according to various embodiments of thepresent invention will be described below.

The sleeve 156 may be slid over the carrier 158 upon the carrier 158couples to the spinal fixation element 160. As such, the location wherethe carrier 158 engages the spinal fixation element 160 is protected bythe sleeve 156 to prevent inadvertent decoupling of the spinal fixationelement 160 from the carrier 158. In an exemplary embodiment of thepresent invention, the sleeve 156 may include an angular cut 142 and thecarrier 158 may include a protrusion, such as a pin, that slides in theangular cut 142 of the sleeve 158. The pin and the angular cut 142 allowthe sleeve 156 to move forward and backward over the carrier 158. Thepin moves within the angular cut 142 when the user twists and slides thesleeve 156 over the carrier 158. The sleeve 156 may be provided with agrooved surface portion 144 to improve the user's grip on the extensionelement 150 and to facilitate twisting of the sleeve 156 over thecarrier 158.

The spinal fixation element rotation instrument 100 illustrated in FIGS.1A-1B is formed of two lever arms 102 and 104. The first lever arm 102and the second lever arm 104 may be provided with surface features 116for improved ergonomics and improved control over the spinal fixationelement rotation instrument 110. A first ratchet 108 is provided at thedistal end of the first lever arm 102. A second ratchet 110 is providedat the distal end of the second lever arm 104. The first ratchet 108 andthe second ratchet 110 are coupled to each other. The proximal end 154of the extension element 150 couples to the spinal fixation elementrotation instrument 100 by fitting through the first ratchet 108 and thesecond ratchet 110. The rotation of the first ratchet 108 and/or thesecond ratchet 110 rotates the spinal fixation element 160 coupled tothe extension element 150. The rotational direction of the spinalfixation element 160 depends on the rotational direction of the firstratchet 108 and/or the second ratchet 110. One of ordinary skill in theart will appreciate that the first ratchet 108 and the second ratchet110 may couple to a variety of modular tips and that the modularity isnot limited to the extension element 150.

The extension element 150 may be provided with a plurality of markers toillustrate how much the extension element 150 has rotated within thedistal end 106 of the spinal fixation element rotation instrument 100.

The extension element 150 may also include a coupling/decouplingmechanism 146 for coupling and decoupling the extension element 150to/from the spinal fixation element rotation instrument 100. FIG. 2Aillustrates a cross-sectional view of the extension element 150 coupledto the distal end of the spinal fixation element rotation instrument100. FIG. 2B illustrates a cross-sectional view of the extension element150 and the decoupling mechanism 146 provided at a proximal end 154 ofthe extension element 150. FIG. 2C illustrates a cross-sectional view ofthe distal end 106 of the spinal fixation element rotation instrument100. The coupling/decoupling mechanism 146 may comprise a loaded spring200 that is used to lock the extension element 150 in the distal end 106of the spinal fixation element rotation instrument 100. By pressing onthe coupling/decoupling mechanism 146, the user compresses the loadedspring 200. When the user places the extension element 150 through thedistal end 106 of the spinal fixation element rotation instrument 100,the loaded spring 200 decompresses and pushes the ball 147 provided on aproximal end 154 of the extension element 150 outward. As illustrated inFIG. 2C, one or more grooves 107 may be provided in an internal surfaceof the first ratchet 108 and/or the second ratchet 110. The ball 147falls into one of the grooves 107 provided on the internal surface ofthe distal end 106 of the spinal fixation element rotation instrument100. When the ball 147 is in the groove 107, the extension element 150is locked in the distal end 106 of the spinal fixation element rotationinstrument 100. The user may press on the coupling/decoupling mechanism146 to disengage the ball 147 from the groove 107, unlocking theextension element 150 from the spinal fixation element rotationinstrument 100.

One of ordinary skill in the art will appreciate that thecoupling/decoupling mechanism 146 described above is for illustrativepurposes only and similar mechanisms may be used to couple the extensionelement 150 to the spinal fixation element rotation instrument 100.Moreover, the proximal end 154 of the extension element 150 may have avariety of shapes and sizes. The spinal fixation element rotationinstrument 100 may be provided with an appropriate distal end 106 thatmatches the shape and size of the proximal end 154 of the extensionelement 150.

According to various embodiments of the present invention, additionalmodular tips may be provided to facilitate the coupling between thespinal fixation element rotation element 100 and the extension element150. A first end of the modular tip couples to the distal end of thespinal fixation element rotation instrument 100 and a second end,opposite to the first end, couples to the proximal end of the extensionelement 150. The first and second ends of the modular tips may be, forexample, circular, hexagonal, diamond shape, etc. according to the shapeof the distal end 106 of the spinal fixation element rotation instrument100 and the proximal end 154 of the extension element 150.

According to another exemplary embodiment of the present invention, thespinal fixation element rotation instrument 100 may directly couple tothe spinal fixation element 160 eliminating the extension element 150.In this exemplary embodiment, the spinal fixation element 160 may fitthrough a portion of the first ratchet 108 and/or the second ratchet110. The spinal fixation element 160 may have surface features such asthreads or grooves that enable a portion of the first ratchet 108 and/orthe second ratchet 110 to grab on the spinal fixation element 160. Thespinal fixation element 160 may be of any shape and size, including butnot limited to, hexagonal, square, round, diamond, etc.

FIGS. 3A-3B illustrate two exemplary spinal fixation elements 160according to various embodiments of the present inventions. Asillustrated in FIG. 3A, the proximal end 164 of the spinal fixationelement 160 may have a hexagonal shape. FIG. 3B illustrates anembodiment of the present invention where the spinal fixation element160 is provided with a rounded proximal end 166. The distal end 162 ofthe spinal fixation elements 160 illustrated in FIGS. 3A and 3B may beof any shape. According to various embodiments of the presentapplication, the spinal fixation elements, such as those illustrated inFIGS. 3A and 3B, may also be used by reversing the distal end and theproximal end of the spinal fixation elements. FIGS. 4A-4C illustrate anexemplary embodiment where the distal end 164 of the spinal fixationelement 160 illustrated in FIG. 3A becomes the proximal end 402 and iscoupled to the extension element 150. The proximal end 162 of the spinalfixation element 160 illustrated in FIG. 3A becomes the distal end 404and is inserted into the patient.

FIGS. 4A-4C illustrate an exemplary mechanism 400 to couple the spinalfixation element 160 to the extension element 150. As illustrated inFIG. 4A, the carrier 158 is provided with a grabbing tip 400. Thegrabbing tip 400 assumes a larger diameter when the sleeve 156 isretracted over the carrier 158, as illustrated in FIG. 4B. The proximalend 402 of the spinal fixation element 160 is inserted in the grabbingtip 400 when the grabbing tip 400 is at an extended position. The sleeve156 is then advanced over the carrier 158 and the grabbing tip 400 so asto cover the grabbing tip 400. When the sleeve 156 is pushed over thegrabbing tip 400, the opening of the grabbing tip 400 closes over theproximal end 402 of the spinal fixation element 160 so as to tightlygrab the spinal fixation element 160.

A portion of the exemplary sleeve 156 illustrated in FIGS. 4A-4C may beprovided with a plurality of threads. The treads may be 5-10 mm. long,provided on a portion of the inner surface of the sleeve 156. Thethreads may engage a portion of the carrier 158. The threads may slowlydisengage from the carrier 158 while the sleeve 156 is retracted overthe carrier 158 to expose the grabbing tip 400. When the threads arecompletely disengaged from the carrier 158, the sleeve 156 may be pulledup to expose the remainder of the carrier 158. The threads may help thesleeve 156 to tighten or loosen up around the carrier 158 and thegrabbing tip 400.

The grooved surface portion 144of the sleeve 156 may provide improvedcontrol to the user over the sleeve 156. The user may twist and rotatethe sleeve 156 around the carrier 158 using the grooved surface portion144 so as to advance or retract the sleeve 156 over the carrier 158. Theextension element 150 illustrated in FIGS. 4A-4C may have acoupling/decoupling mechanism 146 similar to one discussed above tocouple the extension element 150 to the spinal fixation element rotationinstrument 100. The sleeve 156 may also include an external surfacefeature 406 for mating with a second instrument when the spinal fixationelement 160 is in its final place and the extension element 150 needs tobe removed. During removal of the extension element 150, it may bedifficult for the surgeon to get their hand to a position where thesurgeon can loosen the sleeve 156 and detach the spinal fixation element160 from the extension element 150. If this is the case, the secondinstrument, e.g. a hex wrench that mates with the external surfacefeature 406 of the sleeve 156, may be used to grab on the sleeve 156 forrotating it to release the extension element 150 from the sleeve 156.

FIGS. 5A-5B illustrate another exemplary mechanism 500 to couple thespinal fixation element 160 to the extension element 150. As illustratedin FIG. 5B, the internal surface of the carrier 158 is provided with aleaf spring 502. The proximal end 164 of the spinal fixation element 160is provided with a notch 504. When the spinal fixation element 160 iscoupled to the extension element 150, the leaf spring 502 of the carrier158 grabs the notch 504 provided on the proximal end 164 of the spinalfixation element 160. The coupling location of the spinal fixationelement 160 and the extension element 150 is provided within the sleeve156 to prevent unintentional decoupling of the spinal fixation element160 from the extension element 150.

FIGS. 6A-6B illustrate a top view of the spinal fixation elementrotation instrument 100. The first lever arm 102 includes a switch or aknob 112 at the proximal end thereof. Similarly, the second lever arm104 includes a switch or a knob 114 at the proximal end thereof. Theswitch 112 is used to adjust the rotational direction of the firstratchet 108. Similarly, the switch 114 is used to adjust the rotationaldirection of the second ratchet 110. Using the switch 112, the firstratchet 108 may be set to rotate clockwise or counterclockwise. Usingthe switch 114, the second ratchet 110 may be set to rotate clockwise orcounterclockwise. The rotation of the first ratchet 108 or the rotationof the second ratchet 110 rotates the spinal fixation element 160 thatis coupled to the spinal fixation element rotation instrument 100.

As shown in FIG. 6C, when the second ratchet 110 is set to rotate in afirst direction, i.e. clockwise, a right end 604 of the rocker 600engages the teeth 602 of the second ratchet 110. Clockwise rotation ofthe second ratchet 110 rotates the spinal fixation element 160clockwise. As shown in FIG. 6D, when the second ratchet 110 is set torotate counterclockwise, a left end 606 of the rocker 600 engages theteeth 602 of the second ratchet 110. Counterclockwise rotation of thesecond ratchet 110 rotates the spinal fixation element 160counterclockwise. As such, it is possible to control the rotationaldirection of the spinal fixation element 160 using the switches 112 and114 of the spinal fixation element rotation instrument 100.

The rotational direction of the ratchets 108 and 110 is controlled withthe first switch 112 and 114, respectively. When the first ratchet 108is set to rotate in a first direction and the second ratchet 110 is setto rotate in a second direction opposite to the first direction, thefirst ratchet 108 and the second ratchet 110 may lock each other out.When the ratchets 108 and 110 are at a locked out position, the spinalfixation element 160 may no longer be rotated in the distal end 106 ofthe spinal fixation element rotation instrument 100.

FIG. 7 illustrates an exemplary embodiment of the spinal fixationelement rotation instrument 100. As illustrated in FIG. 7, the distalend of the spinal fixation element rotation instrument 100 couples tothe proximal end 154 of the extension element 150. The proximal end 154of the extension element 150 passes through and protrudes from the firstratchet 108 and the second ratchet 110 provided at the distal end of thespinal fixation element rotation instrument 100. The carrier 158 of theextension element 150 is coupled to the spinal fixation element 160 thatwill be implanted during a minimally invasive surgery to correct aspinal deformation or degeneration. A plurality of bone anchors 700 areimplanted on the vertebrae 702. Each bone anchor 700 includes an opening704 provided above the bone surface. The openings 704 of the adjacentbone anchors 700 form a passage 706. The spinal fixation element 160 isfed through the passage 706 using the spinal fixation element rotationelement 100. If the user wants to merely advance spinal fixation element160 in the passage 706, the user may set the lever arms 102 and 104 torotate in opposite direction so as to put the spinal fixation elementrotation instrument 100 in a locked out position. In the locked outposition, the spinal fixation element rotation element 100 serves as aspinal fixation element holder. The spinal fixation element may beintroduced through the incision using the spinal fixation elementrotation element 100 at the locked out position. In addition, the spinalfixation element rotation element 100 at the locked out position mayfacilitate the translation of the rod from a first bone anchor to theadjacent next bone anchor. The user may still rotate the spinal fixationelement 160 by rotating the spinal fixation element rotation element 100similar to a spinal fixation element holder. This will allow the user tomove the spinal fixation element 160 in the surgical site as necessary.However, when it is necessary to controllably rotate the spinal fixationelement 160 in the passage 706, the first and second lever arms 102 and104 of the spinal fixation element rotation element 100 may be set torotate in the same direction so as to rotate the spinal fixation element160.

If the user wants to rotate the spinal fixation element 160 clockwise,the driver arm, e.g. the second lever arm 104, is rotated clockwisewhile the holder, e.g. the first lever arm 102, is held stationary. Theclockwise rotation of the driver arm rotates the second ratchet 110clockwise. The extension element 150 and the spinal fixation element 160are provided in the socket of the second ratchet 110. The clockwiserotation of the second ratchet 110 rotates the spinal fixation element110 clockwise. The first ratchet 108 attached to the holder arm keepsthe extension element 150 and the spinal fixation element 160 fromrotating back toward their initial position, i.e. rotatingcounterclockwise. The driver arm, e.g. the second lever arm 104, isrotated counterclockwise toward to start position to rewind the secondratchet 110. These steps are repeated for further rotating the rodclockwise.

If the user wants to rotate the spinal fixation element 160counterclockwise, the driver arm, e.g. the second lever arm 104, isrotated counterclockwise while the holder, e.g. the first lever arm 102,is held stationary. The counterclockwise rotation of the driver armrotates the second ratchet 110 counterclockwise. The extension element150 and the spinal fixation element 160 are provided in the socket ofthe second ratchet 110. The counterclockwise rotation of the secondratchet 110 rotates the spinal fixation element 110 counterclockwise.The first ratchet 108 attached to the holder arm keeps the extensionelement 150 and the spinal fixation element 160 from rotating backtoward their initial position, i.e. rotating clockwise. The driver arm,e.g. the second lever arm 104, is rotated clockwise toward to startposition to rewind the second ratchet 110. These steps are repeated forfurther rotating the rod counterclockwise.

Using a ratchet with the holder arm results in improved control over theextension element 150 and the spinal fixation element 160. However,according to various embodiments of the present invention, the holderarm may be provided with other mechanisms, such as a strap wrench,instead of a ratchet to interface with the extension element 150. Theholder arm is configured to keep the spinal fixation element 160 or theextension element 150 coupled to the spinal fixation element rotationinstrument 100 in place. One of ordinary skill in the art willappreciate that other mechanisms, such as a strap wrench or a rotationmechanism may be provided at a distal end of the driver arm.

FIGS. 8A-8C illustrate another exemplary embodiment of the spinalfixation element extension instrument 100. As illustrated in FIGS.8A-8C, the driver arm, e.g. the second lever arm 104, may include afirst section 800 and a second section 802 that are coupled togetherusing an attachment mechanism 804 such as a hinge or a loaded springmechanism. The first section 800 may be rotated about a central axis ofthe attachment mechanism 804 so as to be positioned at an angle relativeto the longitudinal axis of the second section 802. At the angledposition, the first section 800 may serve as a handle for rotating thesecond ratchet 110 about the central axis thereof.

Alternatively, the driver arm, e.g. the second lever arm 104 may be amonolithic element. A handle may be attached to the second lever arm 104for easily rotating the second lever arm 104. The handle may be fixed tothe second lever arm 104. Alternatively, the handle may be attached tothe second lever arm 104 using an attachment mechanism such as a hingeso as to be positioned at various angles relative to the second leverarm 104. The handle may enable the user to better maneuver the spinalfixation element rotation instrument 100.

FIGS. 9A-9B illustrate an exemplary embodiment of the spinal fixationelement extension instrument 100 where the first section 800 of thesecond lever arm 104 is provided at an angle about 15° relative to thesecond section 802. The first section 800 may be rotated about thecentral axis of the attachment mechanism 804 so as to form an angleabout 0°-45°, and preferably about 0°-15°, with the longitudinal axis ofthe second section 802. However, the positioning of the first section800 is not limited to the angle illustrated in the figures. The firstsection 800 may be positioned at various angles relative to thelongitudinal axis of the second section 802 to better suit theconditions of the procedure.

In the exemplary embodiment illustrated in FIGS. 9A-9B, the first leverarm 102, i.e. the holder, is held stationary while the second lever arm104, i.e. the driver, is rotated about the central axis of the firstratchet 108 and the second ratchet 110 using the first section 800 ofthe second lever arm 104. The attachment mechanism 804 holds the firstsection 800 in place relative to the second section 802. With therotation of the second ratchet 110, the extension element 150 and thespinal fixation element 160 are rotated.

FIGS. 9A-9B illustrate the spinal fixation element 160 placed throughthe first three bone anchors 700. While the second ratchet 110 enablesthe spinal fixation element 160 to rotate in a first direction, thefirst ratchet 108 keeps the extension element 150 from rotating backtoward its initial position in a second direction opposite to the firstdirection. Thus, the first ratchet 108 prevents the spinal fixationelement 160 from inadvertently rotating in the second direction when thespinal fixation element 160 is in the passage 706. However, if thespinal fixation element 160 is not placed as desired, the surgeon mayretract the spinal fixation element 160 in the passage 706 using thespinal fixation element rotation instrument 100 as a spinal fixationelement holding tool. The surgeon may rotate the spinal fixation element160 as many times as necessary using the spinal fixation elementrotation instrument 100 to place the spinal fixation element 160 in thedesired position.

The spinal fixation element rotation instrument 100 of the presentinvention may be used with a variety of spinal fixation elements. A typeof spinal fixation element is a curved spinal fixation element 650illustrated in FIGS. 10A-10B. Due to the curvature of the curved spinalfixation element 650 or the curvature of the spine at the targetlocation, it may be preferable to insert the curved spinal fixationelement 650 through the skin incision in a first position, such as aconcave position. Once the curved spinal fixation element 650 is placedthrough the openings 704 of one or more bone anchors 700, the curvedspinal fixation element 650 may be rotated to an inverted position, suchas a convex position, using the spinal fixation element rotationinstrument 100. The curved spinal fixation element 650 may be rotatedunder the skin as many times as necessary to accommodate the spinalcurvatures.

FIGS. 11A-11B illustrate a flowchart 950 of steps for placing a spinalfixation element through a plurality of bone anchors. Each bone anchorhas an opening for receiving the spinal fixation element. The user firstsets the rotational direction of the first ratchet and the secondratchet of the spinal fixation element rotation instrument. The firstratchet and the second ratchet of the spinal fixation element rotationinstrument may be set to rotate clockwise (step 952). The rotationaldirection of the ratchets is for illustrative purposes only. Theratchets may be configured to achieve the same results when the ratchetsare set to rotate counterclockwise. According to the embodiments of thepresent invention, when the ratchets are set to rotate in oppositedirections, the ratchets lock each other out. One of ordinary skill inthe art will appreciate that the rotational directional of the ratchetsare for illustrative purposes only and that the ratchets may beconfigured to lock each other out when they are set to rotate in thesame direction.

The spinal fixation element rotation instrument is then coupled to theextension element (step 954). The extension element may already becoupled to the spinal fixation element. Alternatively, the extensionelement may be coupled to the spinal fixation element after the spinalfixation element rotation instrument is coupled to the extension element(step 956). The spinal fixation element and a portion of the extensionelement are inserted through a skin incision (step 958).

During the minimally invasive surgeries, it is possible to insert thespinal fixation element and a portion the extension element through asmall skin incision without inserting the spinal fixation elementrotation instrument through the skin incision, thus reducing the traumato the tissue at the surgery site. Once under the skin, the spinalfixation element is placed through a bone anchor opening (step 960). Ifit is necessary to rotate the spinal fixation element under the skin,the second ratchet may be rotated clockwise from an initial position torotate the extension element and the spinal fixation element clockwisewhile the first ratchet is held stationary (step 962). Step 962 may berepeated as many times as necessary during the operation. The secondratchet is then retracted to the initial position, i.e. the secondratchet is rewound (step 964). If the spinal fixation element is at atarget position (step 966), i.e. placed through the openings of the boneanchors and suitably placed under the skin, the spinal fixation elementis disengaged from the extension element (step 968). The extensionelement carrying the spinal fixation element may be equipped with adecoupling mechanism for controllably decoupling the spinal fixationelement from the extension element. The spinal fixation element isimplanted under the skin, in the patient while the extension element isremoved.

If the spinal fixation element is not at a target position, the userreturns to step 960 and repeats the above discussed steps to positionthe spinal fixation element through the openings of the bone anchors. Itmay be necessary to rotate the spinal fixation element in an oppositedirection, e.g. counterclockwise, for better placement (step 970). Theuser may then change the rotational direction of the second ratchetusing the second switch provided at the proximal end of the second leverarm (step 972) and return to step 960 to repeat the above discussedsteps to position the spinal fixation element. Since the rotationaldirection of the second ratchet is changed, counterclockwise rotation ofthe second ratchet rotate the spinal fixation element counterclockwise.The spinal fixation element is disengaged from the extension elementonce the spinal fixation element is placed in a desired position.

While the exemplary spinal fixation element rotation instrument andmethods disclosed herein have been particularly shown and described withreference to minimally invasive surgeries, those of ordinary skill inthe art will appreciate that the spinal fixation element rotationinstrument described herein may also be used with an invasive, opensurgery. When used in an open surgery, the spinal fixation elementrotation instrument eliminates the need for secondary instruments tohandle the spinal fixation element. The spinal fixation element rotationinstrument according to the present invention will also eliminate theneed to un-grip and re-grip the spinal fixation element betweenrotations during an open surgery. Hence, the spinal fixation elementrotation instrument described herein may reduce the surgery time andreduce the required tools used during an open surgery.

The spinal fixation element rotation instrument 100 described herein maybe constructed of any biocompatible material including, for example,metals, such as stainless steel or titanium, polymers, ceramics, orcomposites thereof. The size and diameter of elements of the spinalfixation element rotation instrument 100 may vary depending on manyfactors including: the type of spinal fixation element 160 and/or thetype of extension element 150 used, the diameter of a surgical accessport or minimally invasive incision for insertion of the spinal fixationelement 160, the depth of the patient, the depth of the tissuesurrounding the target location, etc. In an exemplary embodiment of thepresent invention, the length of the spinal fixation element rotationinstrument 100 may be about 200 mm. The length of the extension element150 may be about 150 mm. The extension element 150 may have a narrowerportion that is configured to fit through the skin incision. Thenarrower portion of the extension element 150 may be about 60 mm. Atypical skin incision fits tightly around the spinal fixation element160 and the narrower portion of the extension element 150 that fitsthrough the skin incision. The diameter of the narrower portion of theextension element 150 may be about 10 mm. These dimensions are forillustrative purposes only and should not be viewed as limiting. One ofordinary skill in the art will appreciate that the lever arms of thespinal fixation element rotation instrument 100 may have any dimension.However shorter lever arm will provide less mechanical advantage andthus, it will be harder to rotate the lever arm.

A person having ordinary skill in the art will appreciate that theaforementioned methods and devices for approximating bone anchors can bemodified depending on the type of anchor being used, as well as thespecific procedure being employed. Moreover, other methods and devicesknown in the art can be used in accordance with the present invention.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

While the instruments and methods disclosed herein have beenparticularly shown and described with reference to the exemplaryembodiments thereof, those of ordinary skill in the art will understandthat various changes may be made in the form and details herein withoutdeparting from the spirit and overall scope. Those of ordinary skill inthe art will recognize or be able to ascertain many equivalents to theexemplary embodiments described specifically herein by using no morethan routine experimentation. Such equivalents are intended to beencompassed by the overall scope and the appended claims

1. An instrument for rotating a spinal fixation element comprising: afirst lever arm, wherein a distal end of the first lever arm is adaptedto couple to the spinal fixation element; and a second lever armrotatably coupled to the first lever arm at the distal end thereof, adistal end of the second lever arm being adapted to couple to the spinalfixation element, wherein the second lever arm rotates relative to thefirst lever arm, about a central axis of the distal ends of the firstlever arm and the second lever arm to rotate the spinal fixation elementfrom an initial position to a rotated position.
 2. The instrument ofclaim 1, wherein the first lever arm includes a first ratchet and thesecond lever arm includes a second ratchet forming a dual ratchetmechanism that prevents the spinal fixation element from rotating backtoward the initial position.
 3. The instrument of claim 1, wherein theinstrument receives the spinal fixation element in a portion of anopening provided at the distal end of the first lever arm and the secondlever arm.
 4. The instrument of claim 1, further comprising: anextension element including a distal end adapted to couple to the spinalfixation element and a proximal end adapted to couple to the instrument,a portion of the extension element fits through a skin incision at atarget site to guide the spinal fixation element under skin.
 5. Theinstrument of claim 1, wherein the distal ends of the first lever armand the second lever arm are removable and replaceable.
 6. Theinstrument of claim 1, wherein the second lever arm comprises: a firstsection; a second section; and an attachment mechanism to attach thefirst section to the second section so that the first section isrotatable relative to the second section about a central axis of theattachment mechanism, wherein the central axis of the attachmentmechanism is perpendicular to the central axis of the distal ends of thefirst lever arm and the second lever arm.
 7. The instrument of claim 6,wherein the attachment mechanism is a hinge.
 8. The instrument of claim6, wherein the attachment mechanism is a loaded spring mechanism thatallows the first section to assume one or more positions relative to thesecond section.
 9. The instrument of claim 2, further comprising: afirst switch provided on a proximal end of the first lever arm, whereinthe first switch allows the first ratchet to rotate clockwise when thefirst switch is at a first position, and the first switch allows thefirst ratchet to rotate counterclockwise when the first switch is at asecond position.
 10. The instrument of claim 9, further comprising: asecond switch provided on a proximal end of the second lever arm,wherein the second switch allows the second ratchet to rotate clockwisewhen the second switch is at a first position, and the second switchallows the second ratchet to rotate counterclockwise when the secondswitch is at a second position.
 11. The instrument of claim 10, whereinthe spinal fixation element is rotated clockwise when the first ratchetand the second ratchet are set to rotate clockwise.
 12. The instrumentof claim 10, wherein the spinal fixation element is rotatedcounterclockwise when the first ratchet and the second ratchet are setto rotate counterclockwise.
 13. The instrument of claim 10, wherein thefirst ratchet and the second ratchet lock each other out so as toprevent the spinal fixation element from rotating when the first ratchetis set to rotate in a first direction and the second ratchet is set torotate in a second direction opposite to the first direction.
 14. Amethod for percutaneous positioning of a spinal fixation element througha plurality of bone anchors placed below fascia, the plurality of boneanchors having an opening adapted to couple to the spinal fixationelement, the method comprising: coupling a proximal end of the spinalfixation element to a spinal fixation element rotation instrumentcomprising two lever arms connected to each other at a distal end of thespinal fixation element rotation instrument, wherein the spinal fixationelement rotation instrument includes a first lever arm and a secondlever arm that rotates relative to the first lever arm about a centralaxis of the distal end of the spinal fixation element rotationinstrument; inserting a distal end of the spinal fixation elementthrough an incision in proximity of a first bone anchor; placing thespinal fixation element through the opening of the first bone anchor;and guiding the spinal fixation element though a second bone anchoradjacent to the first bone anchor.
 15. The method of claim 14, furthercomprising: rotating the spinal fixation element from an initialposition to a rotated position within the distal end of the spinalfixation element rotation instrument by rotating the second lever armrelative to the first lever arm while the first lever arm is heldstationary, wherein the first lever arm prevents the spinal fixationelement from rotating back toward the initial position.
 16. The methodof claim 14, further comprising: correcting the placement of the spinalfixation element through the plurality of bone anchors by: retractingthe spinal fixation element through adjacent bone anchors, andre-positioning the spinal fixation element through adjacent boneanchors.
 17. The method of claim 14, wherein the distal end of thespinal fixation element rotation instrument has a dual ratchetmechanism.
 18. A dual ratchet spinal fixation element rotationinstrument comprising: a first ratchet; and a second ratchet connectedto the first ratchet at a distal end thereof, wherein the first ratchetand the second ratchet are configured to couple to a spinal fixationelement or to an extension element coupled to the spinal fixationelement, one of the first ratchet or the second ratchet rotates thespinal fixation element in a first direction from an initial position toa rotated position, other of the first ratchet or the second ratchetprevents the spinal fixation element from rotating back toward theinitial position.
 19. The dual ratchet spinal fixation element rotationinstrument of claim 18, further comprising: a first switch provided at aproximal end of the first ratchet, wherein the first switch configuresthe first ratchet to rotate clockwise when the first switch is at afirst position, and the first switch configures the first ratchet torotate counterclockwise when the first switch is at a second position.20. The dual ratchet spinal fixation element rotation instrument ofclaim 19, further comprising: a second switch provided at a proximal endof the second ratchet, wherein the second switch configures the secondratchet to rotate clockwise when the second switch is at a firstposition, and the second switch configures the second ratchet to rotatecounterclockwise when the second switch is at a second position.
 21. Amethod for positioning of a spinal fixation element through a pluralityof bone anchors placed below fascia, the plurality of bone anchorshaving an opening adapted to couple to the spinal fixation element, themethod comprising: coupling a proximal end of the spinal fixationelement to a spinal fixation element rotation instrument having a leverarm; placing the spinal fixation element through the opening of thefirst bone anchor; guiding the spinal fixation element though a secondbone anchor; rotating the lever arm in a first direction to effectrotation of the spinal fixation element about a central axis of thespinal fixation element in the first direction to a rotational position;and rotating the lever arm in a second direction, opposite the firstdirection, while maintaining the spinal fixation element in therotational position.
 22. The method of claim 21, wherein the spinalfixation element is delivered to the first bone anchor through apercutaneous incision.